define add 
proc( n )
  i := n;
  s := 0;
  n := 2;
  while i do s := s + i;  i := i-1 od;
  return s
end;

define addr 
proc(n)
  if n then return n + addr(n-1) else return 0 fi
end;

n := 0 - 5; 
if n then i := n else i := 0 - n fi; 
fact := 1; 
while i do fact := fact * i; i := i - 1 od
